THE PRAIRIE NATURALIST
Volume 16, No. 3
.
September 1984
Big Game Habitat Use in
Southeastern Montana
James G. MacCracken1 and Daniel W. Uresk2
USDA, Forest Service,
Rocky Mountain Forest and Range Experiment Station
Rapid City, SD 57701
INTRODUCTION
The loss of suitable, high quality habitat is a major problem facing big game
managers in the western United States. Agricultural, water, road and highway,
housing, and recreational development have contributed to loss of natural big
game habitat (Wallmo et al. 1976, Reed 1981). In the western United States,
surface mining of minerals has great potential to adversely affect localized big
game populations (Reed 1981). Helms (1978) discussed negative and positive
impacts of mine development on pronghorn (Antilocapra americana) in Wyoming. He reported an actual increase in pronghorn populations near Douglas,
Wyoming, despite mining developments. Information on mining impacts on
other big game species is scarce. To date, not enough time has elapsed to adequately evaluate these impacts, but displacement of big game in the immediate
area disturbed by mining is likely (Amstrup 1978).
To adequately assess the impacts of surface mining on big game, data on
population levels and habitat use must be collected throughout all phases of
mining operations. Bentonite mining has occurred over the last 3 years in
southeastern Montana and northeastern Wyoming. Bentonite mining has been
much more extensive in Wyoming than Montana. Only a small portion of our
study area had been previously mined.
The objectives of our study were to examine big game abundance and habitat
use in southeastern Montana prior to extensive bentonite mining.
STUDY AREA AND METHODS
The study was conducted from April 1979 through March 1981 in
southeastern Montana immediately west of the town of Alzada and encompasses
about 11,300 ha of native rangeland. Elevations range from 1036 to 1128 m,
and annual precipitation averages 37 cm.
Plant communities present on the study area were: sagebrush-grasslands,
hardwood forest along stream courses, and ponderosa pine (Pinus ponderosa)
forest at higher elevations. Soils consisted of alluvial clayey deposits and shale
1
MacCracken was research associate with Range Science Department, Colorado State University,
Fort Collins. Present address: SR Box S1370, Fairbanks, AK 99701.
2
Uresk is research biologist with the Rocky Mountain Forest and Range Experiment Station, in
cooperation with South Dakota School of Mines and Technology, Rapid City, SD 57701
135
at higher elevations. Surface deposits of bentonite clay were numerous.
Aerial surveys, using a small fixed-wing aircraft, were made monthly to ascertain big game distribution and abundance. Flights were conducted on two consecutive mornings during the second week of each month. A total count of
animals present was attempted by flying the entire area along north-south belt
transects (Caughley 1977), 0.5 km wide, at about 6 0 m altitude. Observers included the pilot and two biologists. Big game observed were counted and identified by species, recorded as to which plant community they originally occupied,
and locations plotted on a map.
Big game population densities were calculated as the number of animals per
100 km2 of each plant community per day. A 3-way analysis of variance was
used to test for differences in big game population density among plant communities, big game species, and seasons. Tukey’s method was used as a mean
separation test to determine which factors accounted for differences (P<0.05)
in big game densities. December through February comprised the winter season;
March through May, spring; June through August, summer; and September
through November, fall.
Plant community characteristics were measured during summers 1979 and
1980. Four sample sites were examined in both the sagebrush-grass and hardwood forests, and two sample sites in the pine forest. Sample sites were chosen
to be representative of a plant community. The number of replications of sample sites in each plant community were based on community variability and/or
the land area occupied. At each sample site, canopy cover of plants was estimated
along three 50-m line transects, 30.5m apart. Fifty quadrats (2 x 5 dm), spaced
at 1-m intervals, were examined on each transect (Daubenmire 1959). The
number of trees per hectare was estimated by counting all individuals in a 50
x 50-m plot at each sample site. Plant names follow Scott and Wasser (1980).
RESULTS
Vegetation mapping indicated that sagebrush-grass occupied 74% of the
study area. The most abundant plants in that type were big sagebrush (Artemisia
tridentata), common buffalograss (Buchloe dactyloides), blue grama (Bouteloua
gracilis), plains pricklypear (Opuntia polyacantha), Hood phlox (Phlox hoodii),
and common yarrow (Achillea millefolium). Hardwood forest occurred along
stream bottoms and occupied about 14% of the study area. Major plants were
boxelder maple (Acer negundo), green ash (Fraxinus pennsylvanicus), snowberry
(Symphoricarpos sp. ), rose (Rosa spp. ), brome (Bromus spp. ), and bluegrass (Poa
spp.). Pine forest grew on 8 % of the study area. It consisted of ponderosa pine,
Rocky Mountain juniper (Juniperus scopulorum), bur oak (Quercus macrocarpa), western wheatgrass (Agropyron smithii), blue grama, common yarrow, and
starry cerastium (Cerastium arvense). About 3 % of the study area had been mined
for bentonite prior to the initiation of study.
The sagebrush-grass community had the most bare ground. Litter cover was
greatest in both forest types. Canopy cover of grasses and carices was greatest
in sagebrush-grass and hardwood forest areas. Forb cover was nearly equal among
all plant communities, while shrub cover was greatest in hardwood forest and
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sagebrush-grass areas. Tree density was greatest in the hardwood forest community
(Table 1).
Big game observed were mule deer (Odocoileus hemionus), white-tailed deer
(0. virginianus), and pronghorn. Mule deer were the most abundant (P<0.05)
species on the study area, followed by pronghorn (Table 2). Both mule and whitetailed deer were observed more often in hardwood forest than any other plant
community (P<0.05). However, mule deer occupation of pine forest was greatest
in summer followed by spring, while white-tailed deer occupancy was greatest
in fall followed by winter. Pronghorn were observed most often in sagebrushgrass areas but were occasionally seen in the other plant communities. Big game
were observed in greater numbers in spring and summer than fall and winter.
Differences between years in big game density appeared to be unimportant.
Multiple classification analyses indicated that variation in big game population densities during winter and summer accounted for seasonal differences
(P<0.05), hardwood forest areas accounted for differences (P<0.05) in big game
densities among plant communities, and that variation in mule deer density
accounted for differences (P<0.05)
among species.
DISCUSSION
Both hardwood and pine forest communities were important to mule deer
in southeastern Montana. However, hardwood forests supported more mule deer
than pine forests. Severson and Carter 9 concluded that hardwood forest
habitat was critical to mule deer survival on the northern High Plains. Mackie
(1970) stated that pine/juniper woodlands of northern Montana were heavily
used by mule deer in summer, and concluded that this was seasonally important habitat. Results of this study indicate that the same relationships exist in
southeastern Montana. Severson (1981) discussed these relationships in detail.
White-tailed deer were also most abundant in the hardwood forest community. Zwank et al. (1979) reported that bottomland hardwood forests were critical
Table 1. Canopy cover (%) and tree densities in three plant communities,
southeastern Montana, 1979-80.
Categories
Bare ground
Litter
Grasses and carices
Forbs
Shrubs
Total Covera
Trees / ha
a
Two
Hardwood forest
x & SE
8 + 1
30 +_ 3
39 +, 14
9+4
18 + 6
64 7 5
765 + 308
dimensional cover values.
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Plant community
Sagebrush-grass
x + SE
21 + 1
20 ; 5
40 + 28
5I2
8 + 2
57 + 8
Pine forest
% + SE
12 + 2
46 5
22 T
5 I
2 +
37 7
354 I
6
4
2
1
8
99
Table 2. Mean number of big game animals/ 100 km2 observed during aerial
surveys in three plant communities over four seasons in southeastern
Montana.a
Season
Big game
plant
species and community
Winter
Spring
~-
Summer
Fall
Mule deer
Hardwood forest
Sagebrush-grass
Pine forest
40f
8
31
90agh
6a
44mnu
155bij
1bc
56cop
78dekl
1d
10e
21
0
5
6g
0
0m
4i
0
0o
18k
0
13
White-tailed deer
Hardwood forest
Sagebrush-grass
Pine forest
Pronghorn
Hardwood forest
Sagebrush-grass
Pine forest
0f
22
0
a
Values followed by same letter differed
columns.
6h
28
2n
1j
23
0p
1
0
20
0
(P<
- 0.05) across rows and down
habitat for this species in the midwest Use of forest communities by white-tailed
deer in Oregon was also important (Suring and Vohs 1979). White-tailed deer
use of ponderosa pine forest was restricted to fall and winter periods in this study.
Sagebrush-grass areas provide critical habitat for pronghorn on the study area.
Use of other plant communities by pronghorn was minimal.
Aerial surveys were
game during other parts
in habitat use by mule
during night in South
conducted only in the morning and habitat use by big
of the day may change. Steigers (1981) reported a shift
deer fawns from woody draws by day to open prairie
Dakota.
Commercial grade bentonite occurs in scattered pockets, which has resulted
in small, disturbed areas within undisturbed vegetation on the study area. Bentonite mining as currently practiced appears not to have had a serious impact
on big game populations on the study area. However, lack of premining data
precludes more definite statements. When demand for bentonite is high, it may
become profitable to mine lower quality bentonite deposits, which will result
in larger areas being disturbed, and thus, potentially cause greater impacts on
big game populations.
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ACKNOWLEDGMENTS
We thank the Fosters of Wyotana Ranch, the Carlton Grazing Association,
Lynn Alexander, and G. Brimmer for cooperation in this study.
LITERATURE CITED
Amstrup, S. C. 1978. Activities and habitat use pattern of pronghorns on Montana and Wyoming coal lands. Proc. Pronghorn Antelope Workshop
8:270-306
Caughley, G. 1977. Sampling in aerial survey. J. Wildl. Manage. 41:605-615.
Daubenmire, R. 1959. A canopy-coverage method of vegetation analysis. Northwest Sci. 33:43-64.
Helms, B. 1978. Antelope and energy development. Proc. Pronghorn Antelope
Workshop 8:206-2 15.
Mackie, R. J. 1970. Range ecology and relations of mule deer, elk, and cattle
in the Missouri River Breaks, Montana. Wildl. Monogr. 20.
Reed, D. F. 198 1. Conflicts with civilization Pp. 509-5 35 in Mule and blacktailed deer of North America (0. C. Wallmo, ed. ). University Nebraska Press,
Lincoln.
Scott, T. G., and C. H. Wasser. 1980. Checklist of North American plants for
wildlife biologists. The Wildlife Society, Washington, D.C.
Severson, K. E. 1981. Plains habitats. Pp. 459-485 in Mule and black-tailed
deer of North America (0. C. Wallmo, Ed.). University. Nebraska Press,
Lincoln.
Severson, K. E., and A. V. Carter. 1978. Movements and habitat use by mule
deer in the Northern Great Plains, South Dakota. Pp. 466-468 in Proc. First
Int. Rangelands Congr. (D. W. Hyder, ed.). The Society for Range Management, Denver.
Steigers, W. D., Jr. 1981. Habitat use and mortality of mule deer fawns in
western South Dakota. Ph.D. Dissertation. Brigham Young University, Provo, Utah.
Suring, L. H., and P. A. Vohs, Jr. 1979. Habitat use by Columbia white-tailed
deer. J. Wildl. Manage. 43:610-619.
Wallmo, 0. C., D. F. Reed, and L. H. Carpenter. 1976. Alteration of mule
deer habitat by wildfire, logging, highways, agriculture, and housing
developments. Pp. 37-47 in Mule deer decline in the west, a symposium (G.
W. Workman and J. B. Low, eds.) Utah Agricultural Experiment Station,
Logan.
Zwank, P. J., R. D. Sparrowe, W. R. Porath, and 0. Torgeson. 1979. Utilization of threatened bottomland habitats by white-tailed deer. Wildl. Soc. Bull.
7:226-232.
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